“There’s an Ant-Man AND a Spider-Man?” – One of the many chuckle-inducing moments in “Avengers: Infinity War” in which even the characters are having trouble keeping track of all the characters.

Before you settle in for the massively enjoyable and just plain massive candy-colored thrill ride adventure that is “Avengers: Infinity War,” keep in mind this is Part One of a two-part adventure.

So don’t expect anything approaching a resolution in this, the 19th film in the Marvel Universe.

Not that we’re ever going to see Full Marvel Closure in our lifetimes. There’s always another story to tell, another adventure to be had, another character to take center stage, as we’re reminded in the teaser scene(s) that pop up after the obligatory 10-minute end credits crawl.

“Infinity War” might be the biggest and most ambitious Marvel movie yet, but it’s certainly not the best. (I’d put it somewhere in the bottom half of the Top 10.) However, there’s plenty of action, humor and heart — and some genuinely effective dramatic moments in which familiar and beloved characters experience real, seemingly irreversible losses.

One of the elements setting “Infinity War” apart from far too many superhero movies is the introduction of a villain who’s more than just another fire-breathing, multi-tongued monster-god hell-bent on destroying everything in its way while mouthing platitudes through some kind of filter that makes him sound like he watched “Star Wars” a thousand times and was always rooting for Darth Vader.

To be sure, the gigantic, all-powerful, merciless Thanos (voiced and performed by Josh Brolin in perhaps the film’s most interesting performance) is a genocidal maniac who DOES want control of all living things — but according to his twisted and demented and damaged mindset, if he can arbitrarily remove half the population through a snap of his mighty fingers, he’ll actually be saving the universe by thinning out the population to a manageable number.

Also, Thanos is actually capable of love — and of making a heartbreaking sacrifice in the name of what he believes to be a greater good. Rarely has the seemingly unstoppable evil force in a comic-book superhero film been given such a richly dramatic background and so many scenes in which there’s actual dialogue and not just CGI-laden battle sequences.

In order to carry out a plan that will eliminate trillions of lives from the galaxies, Thanos needs to obtain all six of the brightly colored Infinity Stones, which are scattered among the planets. (Each time Thanos gains control of a stone, he drops it into place on the fingers of his enormous glove. That’s right: Thanos is bedazzling the heck out of that big armor glove thingy.)

When Mark Ruffalo’s Bruce Banner/Hulk (last seen in “Thor: Ragnorak”) returns to Earth after an extended absence to warn his fellow Avengers of the coming storm, Tony Stark tells him they’ve broken up and aren’t even in touch any more.

“Broken up?” says the baffled Banner. “Like a group? Like the Beatles?”

Yes, Bruce. Like the Beatles.

Once the severity of the crisis is evident, most of the feuds and squabbles and self-interests are set aside, with Steve Rogers (Chris Evans), Spider-Man (Tom Holland), Thor (Chris Hemsworth) and Black Widow (Scarlett Johansson), among others, teaming up to save not only the world, but the universe.

“Infinity War” kicks into a particularly exhilarating gear when the action shifts to Wakanda, where Chadwick Boseman’s Black Panther gathers his armies and joins the fight; the genius Dr. Bruce Banner is stunned by the amazing mind of Shuri, and the great warrior Okoye (Danai Gurira) gets one look at the powers of the Scarlet Witch (Elizabeth Olsen) in battle and exclaims, “What was she doing [back in the lab] all this time”!

Ah, but of course this is more than a mere Avengers All-Star movie, as we also have the very welcome presence of the Guardians of the Galaxy, who provide most of the comic relief (along with a few moving dramatic touches). When the mighty and stunningly handsome Thor literally crash-lands on the windshield of their ship, Drax (the always likable Dave Bautista Jr.) marvels at this god: “It’s as if an angel and a pirate had a baby,” as Gamora literally massages Thor’s muscles, apparently in an attempt to revive him, while Star-Lord (Chris Pratt) stews.

Thor takes a liking to Rocket (Bradley Cooper), whom he calls “The Rabbit,” and he innocently calls the rest of the Guardians “morons” because he thinks that’s what they call themselves.

Oh geez, and we’ve yet to mention the presence of the fantastic Benedict Cumberbatch as Dr. Strange, Sebastian Stan as the un-brainwashed White Wolf, Tom Hiddleston’s ever-duplicitous Loki, Idris Elba’s Heimdall, Benicio del Toro’s The Collector and Peter Dinklage in a role sure to delight anyone who loves Peter Dinklage, and who in the world doesn’t love Peter Dinklage?

At times it’s nearly impossible to keep track of all the Guardians and Avengers who are banding together on Earth and on far-flung planets such as Knowhere and Titan. “Infinity War” has just enough self-awareness without becoming too jokey or winking at the audience. When Spider-Man rescues a number of the Guardians and says, “I got you, I got you, I got you! I’m sorry I haven’t learned everyone’s names!,” it’s just the right light comedic touch at just the right moment.

The final moments of “Infinity War” are haunting and impactful and mysterious, taking us to a nearly hopeless place but of course leaving the door open for a bigger and possibly even more ambitious second chapter.

And yes, you should stick around for the end credits, and a hint of what’s to come.

★★★1⁄2

Marvel Studios presents a film directed by Anthony and Joe Russo and written by Christopher Markus and Stephen McFeely. Rated PG-13 (for intense sequences of sci-fi violence and action throughout, language and some crude references). Running time: 156 minutes. Opens Friday at local theaters.